Shock absorber for airplanes



May 24, 1938. J WALLACE 2,118,455

SHOCK ABSORBER FOR AIRPLANES Filed July 2, 1956 2 Sheets-Sheet 1 7 7 9f6 Z I 7 2 ,22

INVENTOR. c L/OH/V E M/ALLACE ATTORNEYS.

May 24, 1938. J. F; WALLACE SHOCK ABSORBER FOR AIRPLANES Filed July 2,1936 2 Sheets-Shee192 ATTORNEYS Patented May 24 1938 'sHooK ABSORBER;yon; AIRPLANES John F. Wallace, Cleveland, Ohio,. assignor to TheCleveland Pneumaticv ,Tool Cleveland, Ohio, a corporation of OhioCompany,

Application July 2, 1936, Serial No. 88,621

- 7 Claims. Cl. 2 6fl64) This I invention relates to improvements in Ishock absorbers'for airplanes, and 'has reference particularly to meansfor preventing the relative rotation of the telescoping members of ashock absorber. These members are frequently subjected to heavytorsional strains, as for instance where the shock absorber carries aground wheel at itslower end, and no provision outside of. the shockabsorber itself is made for holding the wheel in its desired plane andcounteracting the tendencytoward deflection of the wheel resulting whenit strikes an obstacle.

One of the objects of :the invention is the provision of means carriedby the shock absorber,

but entirely outside of the telescoping cylinders,

for preventing relative rotation of the cylinders.

Another object is the provision of means oi this character which shallstand closest to the shock absorber and be least effective when theairplane is in the air or at the point of landing and torsional strainsare ata minimum, and shall project furthest from the shock absorber andbe most effective when the airplane is on the ground and its weight issupported entirely by the shock absorbers.

Other objects and features of novelty will appear as I proceed with thedescription of that embodiment of the invention which, for the purposesof the present application, I have illustrated in the accompanyingdrawings, in which airplane.

Fig. 2 is a side elevational view of the shock absorber on a largerscale.

Fig. 3 is a detail view partly in'section of a new device which I term atorque knee, and

Fig. 4 is a detail sectional view substantially on the line 44 of Fig.2, showing the hinge mountings for the torque knee.

In the drawings, l0 represents the upper cylinder of a hydro-pneumaticshock absorber. Its outer extremity is connected by any suitable means,such as by an externally threaded circular 45 flange 9, with a frame'supported bracket 9' of the airplane or a wing thereof, to which it isrigidly attached. A pair of lips II are provided for the reception of asuitable brace II to assist in maintaining the mounting of the cylinder.

Within the cylinder I0 there is a piston I2 carried upon a tubularpiston rod or telescoping cylinder l3, which projects of course beyondthe open end of the cylinder). The projecting end of cylinder I3 isinternally-threaded to receive 'a' 5' bracket 6 which, after beingscrewed home, is locked against turning by suitable means. This brackethas a hub portion in which is mounted a wheel spindle l4. It alsocarries a brake flange l5. When the shock absorber is assembled on an 60airplane the spindle ll of course stands trans- Fig. 1 is a sideelevational view of a shock ab- -sorber embodying the invention appliedto, an

versely of the machine. 'I'he wheel spindle of an airplane frequentlyhas a cantilever mounting, as

in thepresent instance, which produces heavy torsional strains wheneverthe wheel 8 strikes an obstruction, but even with an axle mo'untingwherein theya'xle is supported at both ends, the .torsional strains onthe shock absorber may be considerable due to .the twisting effectexperienced when the'wheel strikes such an obstruction.

The cylinder III at its lower extremity has secured thereto a collar l6from which there protherein, the perforations extending transversely ofthe airplane or parallel to the spindle M. The upper end of the torqueknee is hingedly mounted between these ears.-

rjects a pair of ears I! with aligned perforations- Referring now to thedetail construction of the torque knee, l8 is'a forging having apair ofp'erforatedears i9 which are adapted to fit within the ears 11. Aspacingandbearing sleeve 20is used between the ears iii to which it is welded,and is useful as acontainer for lubricant, which may be introducedthrough a grease connection 2|. ,A bushing I is mounted within thesleeve 20 and within the holes in the ears l1 and i9, so

that new bearing surfaces may be supplied when wear occurs. Through theears l1 and the bushing 1 there extends a bolt 22, with a nut 22' on.one end thereof. The forging [8 comprises, in addition to the ears N, aflat plate 23 having several cut-outs for thepurWse of reducing theweight of the part. The two forgings ill at opposite ends of the. torqueknee are identical, and the plates 23 in each case are used forattachment to the legs of the torque' knee. These legs may be built up'of two steel tubes 24 and 25. Each tube at its outer end is slotteddiametrically so as to fit over the plate 23 and'up against a flat head26 i The two tubes 24 and 25 are inclined toward each other and merge atthe knee joint, that is to say they are trimmed off at the proper anglesto form meeting edges which are welded together These ends of the legs,which I term the outer ends inasmuch as they extend away from the' shockabsorber proper, are mounted in f'orgings .along the line indicated at21 in the drawings.

. .28 and 29. These forglngscompri se flat plates I 30 and 3|respectively, that are mounted in slots formed in the merged outer endsof the legs; the tubular elements and the plates 30 and 31 re-'spectively being secured together by welds.

V Theforging 29 beyond the plate-3| is shaped like apartialcylinderfwith flat ends, 'the'latter being perforated to take abolt .32. The forging 28 has a central web 33 with a perforation in themiddle thereof and with a head that is a fragment a cylinder of a sizeto clear the ends of the forging 29 when the joint is assembled. Twoball bearings 3d are positioned upon opposite sidesoi the web it, andthese parts are then 'lhebracket t which carries wheel spindle it hasattached thereto ears 3? and td-having portions embracing and welded tothe hub of the bracket. Between these ears, the ears id of the forgingit are received. The ear 36 is bored to receive a cylindrical nut 39,which projects beyond the ear 38 in both directions and is weldedthereto and also to the brake flange it. A bolt dii is caused to extendthrough the ear bl, one oi the cars it, the sleeve 26, and the other eari9, and is threaded into the nut 39, whereby a hinge connection is madebetween the lower leg oi the torque knee and the piston rod it.

It will be observed that the legs of the torque knee are much wider attheir inner ends than at their outer ends, and that the bolts 22 and it,which constitute the hinge pins between the cylinders and the torqueknee, are relatively long as compared with the bolt or hinge pin 32. Thein ner'hinge joints are accordingly firm and accurate, It is essentialthat these two joints be hinge joints in the true sense of the word. Themiddle joint or knee joint is preferably a hinge joint, although adiflerent type of flexible joint such as a universal joint could beemployed without affecting the functioning of the device, as it isimpossible for the legs to get out of alignment if the hinge connectionswith the telescoping cylinders are free. from play.

in dot and dash lines.

When the-airplane is in flight the connecting rod or inner cylinder ittakes the position indicated by dot and dash lines in Fig. 2, with thelegs of the torque knee in the positions also illustrated At this timethe distance between the knee joint and the axis oithe shock absorber isat the minimum. This is the position, of course, when the ground wheelsflrst touch the ground in making a landing. At this time, that is whenthe plane is supported mostly by its wings, the torsional efiect of anobstruction encountered by the ground wheel is also of minimum amount.As the plane settles to the ground and the shock absorbers take anincreasingly greater proportion of the load the spindle it moves towardits position of Fig. l and its full line position of Fig. 2, and theknee joint moves outwardly. As the load upon the shock absorbersincreases the torsional efiect in the shock absorberof an obstacleencountered by the wheel increases, but at the same time the leverage ofthe torque legs also increases. Hence the present device is such as todo its work most effectively when the demands upon it are greatest.

Having thus described my invention, I claim:

1. In a shock absorber subjected to torsional strains, a pair oftelescoping cylinders adapted to be attached to the elements whoserelative movements are to be cushioned, upper and lower torque legsconnected together at their outer extremities by a flexible joint, andhinge connections between the inner ends oi the legs and the twocylinders respectively, said legs being wide at their inner ends andnarrow at their outer ends, and the hinge connections at their innerends being longer than the width of the joint at the outer ends.

.ends of the legs.

' arrests arm's shock absorber subjected to torsional strains, a pair oftelescoping cylinders adapted to be attached to the elements whoserelative movementsare to be cushioned, upper and lower torque legs ofgreater width than thickness connected together at their outerextremities by a flexible joint, and hinge connections between the innerends oi the legs and the two cylinders respectively, the long dimensionof the transverse section of each leg being parallel to the said hingeconnections, and the hinge connections at the inner ends of the legsbeing longer than the width of the joint at the outer ends of the legs.

3. In a shock absorber subjected to torsional strains, 9. pair oitelescoping cylinders adapted to be attached to, the elements whoserelative movements are to m cushioned, upper andlower connections beinglonger than the outer hinge connection.

t. In a shock absorber subjected to torsional.

v strains, a pair of telescoping cylinders adapted to be attached to theelements whose relative movements are to be cushioned, upper and lowertorque legs connected together at their outer extremities by a flexiblejoint, and hinge connec-- tions between the inner ends of the legs andthe two cylinders respectively, each leg comprising two tubular elementsspaced apart transversely at the inner end of the leg and joined at theouter end.

5. In a shock absorber subjected to torsional strains, a pair oftelescoping cylinders adapted to be attached to the elements whoserelative movements are to be cushioned, upper and lower torque legsconnected together at their outer extremities by a flexible joint, andhinge connections between the inner ends or the legs and the twocylinders respectively, each leg compris ing two tubular elements spacedapart transversely at the inner end of the leg and joined at the outerend, and each leg comprising inner and outer end elements having flatflns,.and the tubular elements having slots receiving said fins.

6. In a shock absorber subjected to torsional strains, 9.. pair oftelescoping cylinders adapted to be attached to the elements whoserelative movements are to be cushioned, upper and lower substantiallytriangular torque legs of greater width than thickness, an outerflexible joint between the legs at the summits of the triangles, andhinged connections between the respective cylinders and the inner endsof the legs at the bases of the triangles.

7. In a shock absorber subjected to torsional strains, a pair oftelescoping cylinders adapted to be attached to the elements whoserelative movements are to be cushioned, upper and lower torque legshaving inner portions of a cross sectional area greater than that of theouter end portions thereof, hinge connections between the inner ends oithe legs and the two cylinders respectively of a torsional capacitycorresponding to the torsional strength oi the large inner ends of thelegs, and a flexible joint between the outer ends oi said legs havingatorsional capacity corresponding to the torsional strength of the outer

